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Re: [PATCH 23/25] xfs: connect up write verifiers to new buffers

To: Phil White <pwhite@xxxxxxx>
Subject: Re: [PATCH 23/25] xfs: connect up write verifiers to new buffers
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Wed, 31 Oct 2012 09:34:37 +1100
Cc: xfs@xxxxxxxxxxx
In-reply-to: <20121030133938.GI18595@xxxxxxxxxxxxxxxxxxxx>
References: <1351146854-19343-1-git-send-email-david@xxxxxxxxxxxxx> <1351146854-19343-24-git-send-email-david@xxxxxxxxxxxxx> <20121030133938.GI18595@xxxxxxxxxxxxxxxxxxxx>
User-agent: Mutt/1.5.21 (2010-09-15)
On Tue, Oct 30, 2012 at 06:39:38AM -0700, Phil White wrote:
> On Thu, Oct 25, 2012 at 05:34:12PM +1100, Dave Chinner wrote:
> > From: Dave Chinner <dchinner@xxxxxxxxxx>
> > 
> > Metadata buffers that are read from disk have write verifiers
> > already attached to them, but newly allocated buffers do not. Add
> > appropriate write verifiers to all new metadata buffers.
> > 
> > Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> > ---
> >  fs/xfs/xfs_alloc.c        |    6 +--
> >  fs/xfs/xfs_alloc.h        |    2 +
> >  fs/xfs/xfs_alloc_btree.c  |    1 +
> >  fs/xfs/xfs_attr_leaf.c    |    4 +-
> >  fs/xfs/xfs_bmap.c         |    2 +
> >  fs/xfs/xfs_bmap_btree.c   |    3 +-
> >  fs/xfs/xfs_bmap_btree.h   |    1 +
> >  fs/xfs/xfs_btree.c        |    1 +
> >  fs/xfs/xfs_btree.h        |    2 +
> >  fs/xfs/xfs_da_btree.c     |    3 ++
> >  fs/xfs/xfs_dir2_block.c   |    2 +
> >  fs/xfs/xfs_dir2_data.c    |   11 +++--
> >  fs/xfs/xfs_dir2_leaf.c    |   19 ++++++---
> >  fs/xfs/xfs_dir2_node.c    |   24 +++++++----
> >  fs/xfs/xfs_dir2_priv.h    |    2 +
> >  fs/xfs/xfs_dquot.c        |  104 
> > ++++++++++++++++++++++-----------------------
> >  fs/xfs/xfs_fsops.c        |    7 ++-
> >  fs/xfs/xfs_ialloc.c       |    5 ++-
> >  fs/xfs/xfs_ialloc.h       |    4 +-
> >  fs/xfs/xfs_ialloc_btree.c |    1 +
> >  fs/xfs/xfs_inode.c        |   14 +++++-
> >  fs/xfs/xfs_inode.h        |    1 +
> >  fs/xfs/xfs_mount.c        |    2 +-
> >  fs/xfs/xfs_mount.h        |    1 +
> >  24 files changed, 135 insertions(+), 87 deletions(-)
> > 
> 
> A few comments:
> 
> > diff --git a/fs/xfs/xfs_attr_leaf.c b/fs/xfs/xfs_attr_leaf.c
> > index bb96c55..5d56886 100644
> > --- a/fs/xfs/xfs_attr_leaf.c
> > +++ b/fs/xfs/xfs_attr_leaf.c
> > @@ -923,7 +923,7 @@ xfs_attr_leaf_to_node(xfs_da_args_t *args)
> >                                         XFS_ATTR_FORK);
> >     if (error)
> >             goto out;
> > -   ASSERT(bp2 != NULL);
> > +   bp2->b_pre_io = bp1->b_pre_io;
> >     memcpy(bp2->b_addr, bp1->b_addr, XFS_LBSIZE(dp->i_mount));
> >     bp1 = NULL;
> >     xfs_trans_log_buf(args->trans, bp2, 0, XFS_LBSIZE(dp->i_mount) - 1);
> > @@ -977,7 +977,7 @@ xfs_attr_leaf_create(
> >                                         XFS_ATTR_FORK);
> >     if (error)
> >             return(error);
> > -   ASSERT(bp != NULL);
> > +   bp->b_pre_io = xfs_attr_leaf_write_verify;
> >     leaf = bp->b_addr;
> >     memset((char *)leaf, 0, XFS_LBSIZE(dp->i_mount));
> >     hdr = &leaf->hdr;
> 
> I'm unclear as to why you're removing the asserts here.  There must be
> a reason that you think bp is guaranteed to be safe, but I haven't
> grasped it here.

If bp is NULL then the code is going to oops immediately, anyway.
Hence the assert is redundant.  Further, the function that returns
bp either gives us a valid buffer or returns an error, so logically
the assert is also redundant from that perspective.

Hence I killed them to clean up the code a little.

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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